Method of and apparatus for treating coffee



y 1943- A. J. HAZLE, JR 2,323,771

METHOD AND APPARATUS FOR TREATING COFFEE Filed Dec. 24, 1938 4 Sheets-Sheet 1 LEW ALBERT J. HAZLE JR.

y 1943 A. J. HAZLE, JR 2,323,771 METHOD AND APPARATUS FOR TREATING COFFEE Filed Dec. 24, 1938 4 Sheets-Sheet 2 :ZLI'

O C) I 0 1/3 o /09 O //0 I07 /08 A B [I I2, I i I 65 j! [05' l me i v 13 I Q 103 i /04 I I 1oz ALBERT J. HAZLE JR.

July 6, 1943. A. J. HAZLE, JR

METHOD AND APPARATUS FOR TREATING COFFEE Filed Dec. 24, 1958 4 Sheets-$heet 5 ALBERT J. HAZLE JR.

July 6, 1943. A. J. HAZLE, JR

METHOD AND APPARATUS FOR TREATING COFFEE Filed Dec. 24, 1958 4 Sheets-Sheet 4 Patented July 6, 1943 METHOf) OF AND APPARATUS FOR TREAT- IN G COFFEE Albert J. Hazle, Jr., Chicago, Ill., assignor to B. F. Gump Co., Chicago, 111., a corporation of Illinois Application December '24, 1938, Serial No. 247,600

6 Claims.

The present invention relates to a method for treating coffee and apparatus by means of which the steps of the method may be practiced, and more particularly to such apparatus and method which may be utilized in connection" with the production of coffees having different charac teristics, such as steel cut and more finely di vided and pulverized coffee.

With the increasing popularity and use of more finely divided and pulverized coffee, as compared with steel cut coffee, it is realized that it would be highly desirable and advantageous to have treating apparatus of a universal character, which could with equal facility be selectively utilized to produce various types of grinds, such as steel cut, semi-pulverized and flour coffee, f

and in which the amount of comminuted chaff in the finished product may be varied. I

While the apparatus and process as described in the above patent is admirably suited and very satisfactory, when utilizedin connection with steel cut of granular coffee, it should possess certain other operating characteristics when it is endeavored to use the apparatus in the processing and treating of more finely divided or pulverized coffee.

As a result of the foregoing discoveries, the present invention contemplates as a primary object the'provision of a universal coffee treating apparatus which may with equal facility be utilized for treating steel cut coffee, as well as more finely divided and pulverized coffee.

Another and further object of the herein described invention is to providein a universal coffee treating apparatus, improved means which may be selectively rendered nonoperative or operative to remove chaff that has been liberated during the reduction of the coffee beans.

Still another object of this invention is to provide in apparatus as described herein and including a chaff separating mechanism, a chaff separating mechanism for removing liberated chaff from a stream of material such as reduced coffee, a novel arrangement for returning to the stream any particles of coffee or material which may be taken outwith the removed chaff.

In accordance with the general features of the herein described invention, it is proposed to utilize the invention in connection with apparatus having a grindinghead of the multiple reduction type, whereby the various size grinds may be selectively produced by adjusting the various reduction rolls by throwing them in and out of grinding position. For example, when it is desired to produce very coarseor cracked coffee, the lower reduction rolls are thrown apart or out of grinding position, thus permitting the co ee to pass therebetween without further reduction. On the other hand, when it is desired to producewhat is generally known as steel cut, the next lower reduction rolls, which are provided with suitable corrugations, are adjusted to-grinding position, the reduction. rolls below these being thrown apart or out of grinding position. Further, when it is desired to produce a finer or pulverized grind, all the reduction rolls are set in grinding position. The foregoing procedure may be varied according tothe usual practice, depending on the size product desired.

As an additional feature, means are provided for removing liberated chaff in the cracked coffee beans in the grinding head by subjecting the stream of cracked coffee particles to an air current which carries the lighter chaff particles to a separating chamber. Of course, in removing the chaff, there is a likelihood that particles of coffee will be carried along with the chaff. Unless these particles are recovered, they will be carried away with the chaff, thereby reducing the efficiency of theapparatus. In order to recover particles of coffee which are'carried away with the chaff, the separating chamber is provided with an outlet door'which is retained closed by the action of partial vacuum. This door is so arranged that it will automatically open at periodic intervals due to theweight ofthe accumulation of coffee particles in the separating chamber to permit the coffee particles to return to the grinding head by the inlet conductor for the air stream utilized in removed chaff.

Other objects and features of thisinvention will more fully appear from the following detailed description taken in connection with the accompanying drawings. It is believed that my novel method will be understood from a description .of the apparatus and that a detailed description of the process will be unnecessary.

In the accompanying drawings which illustrate a preferred form of apparatus and several modifications of certain parts thereof, and in which similar reference numerals refer to simi-' lar features in the different views:

Figure 1 is an elevational view partly in section of an apparatus embodying the present invention for carrying outv my novel process;

Figure 2 is an end view of the same showing chaff separating means connected thereto;

Figure 3 is an enlarged fragmentary sectional view taken through the grinding head of the apparatus and showing the cooperative relationship of the chaff removing mechanism therewith, taken substantially on line III-III of Figure 1;

Figure 4 is a transverse sectional view through the grinding head at the location of the final reduction rolls, showing the manner in which these rolls may be relatively adjusted to operative and non-operative positions, taken substantially on line IV-IV of Figure 1;

Figure 5 is a fragmentary end view of the apparatus having broken away portions to show the cooperative relationship between the final reduction rolls and the conveying mechanism in the granulizing chamber; and

Figure 6 is a sectional view taken through the grinding head to show furtherdetails of the final reduction rolls and their adjusting mechanism taken on line VI-VI of Figure Figure 7 is a view schematically illustrating an alternative drive arrangement for the grinding head rolls;

As shown on the drawings:

In the illustrated embodiment of the present invention, the apparatus for treating coffee is disclosed as in general embodying a grinding head as generally indicated at A for grinding or reducing the coffee and delivering the reduced coffee mass to a treating mechanism generally indicated at B. As shown in Figure 2, there is associated with the grinding head chaff removing mechanism as generally indicated at C. The grinding head and coffee treating mechanism are supported as a unit upon spaced channel rails H and I2 which are connected to and supported upon suitable leg frames I3.

The grinding head, as shown in Figure 3, comprises a casing l4 which forms a grinding chamber and totally encloses the grinding mechanism.

Within the grinding chamber is a wall I5 having vertically spaced concave recesses l6. This wall is connected at its upper end with the casing l4 by means of a sloping portion l1, and at its lowermost end with the casing by means of a horizontal portion l8.

Cracking rolls l9-l9 are journalled in the casing and respectively located in the recesses lG-IS. These cracking rolls coact with a larger cracking roll 20 which is similarly journalled in the casing. The cracking rolls cooperate to form the first and second reduction stages for cracking the coffee beans and delivering the cracked coffee particles together with liberated light, flaky chaff to a third reduction stage.

The coffee beans are delivered to the grinding head through an inlet opening 2i formed in the top of the casing l4. From the opening 2|, the coffee beans are guided to the cracking rolls by a sloping chute member 22 to which a plate 23 is attached that cooperates with a plate 24 upon the member I! for forming a guide chute. Upon the lower side of the member 22, there is disposed an angle member 25 to which a guard or scraper 26 is secured for contacting the surface of roll 20 and preventing the coffee beans from spreading and moving over the top of the roll. The scraper 26 'by virtue of its engagement with the roll 20 also forms an air barrier to prevent the passage of air, as will hereafter become more apparent, from the coffee inlet around the inactive surface portion of the roll 20.

The third reduction stage comprises a pair of rolls 2! and 28 which are journalled in the casing. These rolls are arranged to be driven in opposite directions, and one of the rolls is driven at a greater speed than the other. The surfaces of these rolls are so formed as to provide a further reduction of the cracked coffee particles by a granulating action. Asthe coffee is discharged from the roll 20 and the lower roll l9, it falls onto a perforated deflector 26 which augments the distribution of the coffee over the rolls 2! and 28. I

It will be noted that the portion l8 of the wall l5 may be utilized to support a scraper 29 which has its upper edge closely disposed to the surface of lower roll 49 and its lower edge slightly spaced from 'the surface of roll 28. Cooperating with the portion I 8 to form bafiles between the portions of the casing containing the second set of reduction rolls and the portion of the casing containing the cracking roll, is an inwardly extending and downwardly incl ned casing portion 30 which may have a plate 3| attached to its upper surface. The plate 3| is shown as carrying a suitable wiper 32 which may be of leather or other suitable material. This wiper bears against the surface of the roll 21.

Below the rolls 21 and 28 of the third reductionstage, as shown in Figure 4, a fourth reduction stage is provided in the casing by rolls 33 and 34 which are suitably journalled in the casing in a similar manner to the rolls 2! and 28. The fourth stage rolls are preferably of the type having saw tooth corrugations in their surfaces for further reducing coffee granules to a pulverized state. Cooperating with the rolls 33 and 34 are scrapers 35 and 36, as shown in Figure 5. to prevent material adhering to the roll surfaces during the grinding operation. It will be noted that the scrapers 36 guide the material between the rolls and prevent the material from passing around the inactive surfaces of the rolls.

Both the granulating rolls of the third reduction stage and the pulverizing rolls of the fourth reduction stage are so arranged that they may respectively be moved towards and away from each other for the purpose of regulating the extent of reduction of the coffee particles. Moreover, the adjustment of the pulverizing rolls permits movement of these rolls into operative and non-operative relation with the coffee material from the granulating rolls. Thus, with the pulverizing rolls in operative position, the coffee particles from the granulating rolls must pass between the pulverizing rolls and be further reduced, whereas if the pulverizing rolls are moved apart, the coffee particles from the granulating rolls may pass between the pulverizing rolls without being further reduced. It will therefore be apparent that with this arrangement the grinding head may be utilized to selectively produce granulated or steel cut coffee and pulverized or finely ground coffee as desired, and while in the present instance four reduction stages have been described, any desired number of reduction stages may be utilized.

Similar mechanisms are provided for adjusting roll 21 relative to roll 28, and roll 33 relative to roll 34, the latter roll in each case having its journals rigidly mounted in the casing l4. The

- 'journals of the rolls 2! and 33 are mounted for movement relative to the casing, and it is thought that a description of the adjusting mechanism as applied to one of these rolls will be sufficient to understand the arrangement.

As-shown in Figure 4, the journals of roll 33 are each carried at the outer end of an arm 31 of a bell crank 38 which is pivoted on the casing as shown at 39. This bell crank has an arm 40 substantially at right angles to the arm 31. At its outer end the arm 40 is provided with a bolt 4| threadedly adjustable in a longitudinal direction in the end of arm 40. This bolt has one end arranged to engage the surface of an eccentric 42 on a shaft 43 which extends longitudinally of the casing l4 and is suitably trunnioned for retative movements. One end of the shaft 43 carries an actuating lever 44 by means of which the shaft may be rotated. Secured to the shaft 43 for rotation therewith is an'arm 45 carrying a spring detent pin 46 at its free end which is cooperatively associated with a plate 41 on the casing, this plate having a series of holes 48 respectively adapted to receive the detent pin 46 in various adjustments of the lever 44.

'Ihe'end of bolt 4| is urged against the eccentric 42, and the roll 33 is urged toward r011 34 by means of a spring 49 having one end in engagement with one of the journals for this roll and It will be apparent from the foregoing descrip-= tion'that by moving the lever 44, the eccentric 42 acts to move the bell crank 38' in either a clockwise or anti-clockwise direction to bring the roll 33 into closer or further apart relationship with the roll 34.

The chaff removing mechanism C is arranged to variably remove chaiT from the coiTee particles during their passage from the second reduction stage to the third reduction stage, that is, during their passage from the cracking rolls to the granulating rolls. 4

As shown in Figure 2, a chaif collector is disposed at any convenient location adjacent the apparatus. This collector is provided with a pipe 52 which connects with the outlet of a suction fan housed in a casing 53 supported on the grinding head or in any suitable location. The inlet to the suction fan is connected through a conductor 54 which communicates with the top portion of a box-like structure 55. The box-like structure 55 defines a separator or settling chamber for receiving removed chafl" and separating therefrom any cofiee particles which may be contained therein and have been removed from the mill.

This part of the chaif removing mechanism, as shown in Figure 3, is supported as a unit on a plate 56 that is removably secured as by thumb bolts 51'to a spacer frame 55' surrounding an opening 58 formed in the casing lfl adjacent the cracking rolls. The spacer frame at its top has a cut-out portion which forms a slot opening 56 for the admission of air into the casing It for removing any chafi "or coffee particles adhering to the adjacent surface of roll 20. The amount. of air admitted at this point is controlled by a closure plate 51 having appropriate transversely extending slots 58' for receiving thumb bolts 59' for guiding the plate movement and securing it in adjusted position relative to the slot opening.

The pipe 55 at its connection with the box-like structure 55 is provided with a contracted open end 59 so that a portion of the iniet air may be taken in by the suction fan without passing through the separating chamber.

The bottom of the separating chamber is formed by downwardly converging bottom plates 60 and SI for receiving coffee particles. The plate 60 at its lower end margin is provided with a plurality of spaced hinged doors 62 which are each normally maintained in closed position by the partial vacuum created within the separating chamber. The space at the bottom of the chamber adjacent the doors B2 is longitudinally divided by vertical partitions 62' to provide separate outlets for the respective doors so that one door will not interfere with another doorwhen discharging coilee particles or disturb the air intake to such extent as would result in the use of a single large door.

The plate BI is inwardly deflected at its point of convergence with the plate 60 to form a plate portion 64 which cooperates with a downwardly spaced plate 65 to form an air inlet channel having its entrance disposed below the door 62. The innermost end of the plate 65 is terminated adjacent the plate 3|. The innermost end of plate 64 is secured to an inclined plate 56 which has its lowermost edge disposed adjacent the surface of roll 21 and cooperates with plate 3| to form a continuation of the inlet air channel. It will be apparent that inlet air will pass over the surface at roll 21 into the space between the cracking rolls and the granulating rolls where it may come in contact with the cracked coifee particles and particles of light chafi contained therein.

Air is taken from this space and conducted through a channel formed by plate 66 and an upwardly spaced plate 61. The upper marginal edge of plate 5"! is secured to the plate 56 and at the point of communication of this part of the air channel with the interior of the box-like structure 55 is provided with a deflector 68 for directing the air, chafi, and any cofiee particles contained therein towards the bottom of the separating chamber.

The amount of suction in the separating chamber, and consequently the amount of air being drawn into the grinding head may be regulated by means of a slide door 69 on the forward side of the box-like structure, this door being slidably supported so that it may be raised and lowered to admit variable amounts of air to pass directly into the separating chamber and thence through conductor 56. or by closing this door the intake air must enter the mill through the inlet air channel previously described.

By thus varying the amount of air passing into the grinding head, varied amounts of chaff may be removed, as desired. Any coffee particles which may be conducted to the separating chamber will obviously accumulate in the bottom and be separated from the lighter particles of chafi which are drawn toward the top of the separating chamber and pass off into the chaff collector. As the particles of coffee accumulate and their weight against the door increases, the door 62 will open and permit the particles of coiTee to be reconducted through the inlet air channel back to the granulating rolls. As soon as the coffee particles have passed from the separating chamber to the air inlet channel, the door 62 will again close until a sufficient accumulation of coiTee particles has been attained to cause the door to open again.

Should the apparatus be desired without this additional feature of the chaff remover, the plate 56 may be removed and a solid plate secured over the opening 58 in its stead. Removal of plate'56 also carries with it the parts forming the inlet air channel.

The suction. to fan 53 may also be further controlled by a' valve gate Win the conductor pipe 54 as shown in Figure 2. a

The granulizing mechanism B for treating the coilee after it comes from the grinding head, as shown in Figures 1 and 5, includes an elongate trough-like casing H which is supported on and between the channel rails H and I2, this "casing being provided with a rounded bottom. The casing atits inlet end communicates directly with the outlet from the grinding head and receives the colfee and chair particles passing the'rolls 33 and 34. The top of the casing 1| from the grinding head to the outlet end of the casing is provided with a closure plate 12 removably secured in position closing the top of this part of the casing by means of lug and cam connectors 13.

The casing is closed at its ends by end closures 14 and 15 and is longitudinally separated into compartments 16, 11, and 18 by partitions 19 and 80 disposed adjacent the outlet end of the casing. It will be noted that the compartment 16 is open throughout a portion of its top for communication with the grinding head, but is closed by the removable cover from the grinding head to the partition 80. Likewise compartments 11 and '18 are closed at their tops by the cover plate 12.

Extending longitudinally of the casing H and supported upon suitable journals BI and 82 respectively secured to the end closures 14 and 15 is an elongate shaft 83. This shaft extends through the end closures and the partitions 19 and 80.

For continuously conveying the coffee mass containing coffee particles and light chaff particles away from the inlet end of the casing H and to prevent the throwing of coffee particles back against the pulverizing rolls and accumulation of coffee particles around the outlet of the grinding head, particularly in the case of pulverized coffee particles, there is provided a ribbon screw conveyor at this end of the casing which will-smoothly advance the coffee toward the discharge end of the casing without subjecting it to agitation. The ribbon screw conveyor comprises an elongate metallic ribbon 84, which is spiraled about 'the shaft 83 and secured in spaced relation,

to the shaft at spaced points throughout its length by means of radially extending arms 85 which have their outermost ends secured to the ribbon by means of suitable fiat plates 86. It'

will be noted that the several turns of the conveyor are formed from a single ribbon of material. The ribbon is of such length that the spirals may be continued to a point lying withinthe' covered portion of compartment 16.

In constructing this conveyor, many difiiculties were encountered before a conveyor was finally produced which would not throw the coffee mass when run at a relatively high speed, for example 415 to 445 R. P. M.

It was found that a satisfactory conveyor which would advance the material substantially as a whole at a uniform rate and would not throw the material could be obtained by constructing the conveyor with each helix formed at substantially an angle of 13 relative to a cutting plane at right angles to the shaft, and by making the spiral pitch substantially less than the spiral diameter.

At the operating speed of the conveyor, the coffee mass will be moved away from the inlet end of the casing 1| continuously and at the rate at which the material is being delivered from the grinding head.

Within the covered portion of the compartment 16, and also within the compartment 11 there are provided aplurality of whipping arms 81 which are arranged in staggered relation on the shaft 83. These arms have terminal blades 88 which are directed at an angle that will cause the coffee mass received from the ribbon conveyor to be advanced at intervals.

Due to the change from continuous advancement to interval advancement of the coffee mass, the coffee mass will be accumulated within the covered portion of compartment"; and subjected to the whipping action of the arms 81, which will agitate the coifeeparticles and set up an abrading action which comminutes the chaff and comingles it with the coffee particles so that the chaff is rendered invisible by being concealed in the coffee particles.

It has been found that the accumulation of coffee particles, particularly in the case of puladjacent the partition 80, it is freed to pass into compartment 11 through an opening 89 in the partition 80, as shown in Figure 9. It will be noted that the opening 89 is disposed above the bottom of the casing 1I so that there must be a substantial accumulation of coffee before it may pass into compartment 11. It has been found that the arms 81 are more effective in the agitation and beating of a substantial mass of coffee. The coffee in compartment 11 is subjected to a further beating action and is discharged therefrom into compartment 18 as soon as there has been a sufiicient accumulation to open a hinged gate or door 90 in partition 19, as shown in Figure 1, this door being normally held in closed position by the action of gravity on a suitable weight 9| carried by the door.

From compartment 18, the coffee particles containing the comminuted particles of chaff are discharged through an outlet nozzle 92 at the bottom of the compartment.

Referring to Figure 2, the leg frames I3 are preferably secured at their bottoms to a platform base I02 which also provides a support for a driving motor I03. The driving shaft of this motor carries a driving sprocket I04 which is connected to a sprocket I05 on the shaft 83 by means of a chain I06. I

The rolls 33 and 34 are respectively driven through sprockets I01 and I08 by means of a chain I09 which is driven from a sprocket. (not shown) on shaft 83, this chain also being trained over an eccentrically adjustable chain tightening sprocket H0.

The rolls 21 and 28 are similarly provided with sprockets III and H2 over which a-- chain H3 is trained and driven by a separate sprocket (not shown) on the shaft 83. An eccentrically adjustable tightening sprocket H4 is likewise provided in this case.

The cracking rolls, as shown in Figure 1, are

driven from the opposite ends of roll 28 through a suitable connection within a housing H5, in conjunction with other connections contained within a housing I I6, as shown in Figure 5, in the conventional manner.

As shown in Figure 1, it is preferred. to pro-- vide an enclosing casing 1 for concealing the driving sprockets and chains associated therewith for the rolls.

As an alternative driving arrangement to that just described, there is schematically illustrated journals and permits their being interchanged.

From the foregoing description, it will be apparent that the present invention provides improved apparatus and method for treating coffee; coffee treating apparatus of universal character which may be utilized for producing different grinds of coffee, such as steel cut and pulverized; which may have variable amounts of chaff removed therefrom; which is particularly adapted for the treating of finely ground or pulverized coffee and is so arranged that the coffee particles will not become overbeaten and thereby discolored; which embodies novel chaff removing mechanism; and which utilizes novel conveying and agitating mechanism for comminuting the chaff and commingling it with the coffee particles.

I am aware that numerous details of the construction of the apparatus and details. of the process carried out by such apparatus may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention:

1. In a coffee mill including a casing, means in said casing for cracking coffee beans, means defining an air inlet channel for conducting air from the exterior of the easing into the stream of cracked coffee and chaff contained therein for removing the chaff and any coffee particles carried along with the chaff, means defining an air outlet channel for conducting the air together with the removed chaff and any coffee particles contained therein to the exterior of the casing, a

chamber outside the casing connected to-said air outlet for separating the chaff and any coffee particles contained therein, and means for returning the separated coffee particles to the air inlet channel for return with the inlet air to the stream of cracked coffee.

2. The process of preparing coffee which comprises the subjecting of coffee beans to multiple stages of reduction foreffecting a coffee stream between certain of said stages containing granular or pulverized coffee particles and liberated chaff particles, passing an air stream between an air. inlet path and an air outlet path, the air stream during its movement between said paths engaging the coffee stream for removing chaff therefrom together with any cofiee particles carried along with the chaff, separating the removed chaff and any coffee particles carried along with it from the coffee stream and thereafter conducting the separated coffee particles by the inlet air path to the coffee stream to return them to substantially the same location in the coffee stream from which they wereremoved.

3. In a coffee treating apparatus, a casing having a coffee inlet,'a rotating cracking roll in communication with said inlet, and a rotating reduction roll below the cracking roll, means for removing from the stream of cracked coffee chaff and any coffee particlesthat may be carried along therewith and returning the coffee particles removed with the chaff back into the stream prior to its reaching the reduction roll, said means including an inlet air conductor extending into said casing, an air outlet conductor extending into said casing, said conductors having adj acent open inner ends disposed to pass the air flowing therebetween into the coffee stream between the cracking and reduction rolls, and means connected with said conductors for separating the removed chaff and coffee particles and delivering the separatedout coffee'particles to the air inlet conductor for return to the coffee stream.

4. In a coffee treating apparatus, including a casing having a coffee inlet and a rotating cracking roll in communication with the inlet, means for removing chaff from the cracked coffee and any coffee particles that may be carried along with the removed chaff, said means including an air outlet conductor extending past the cracking roll in close proximity to its cracking surface and having an open end adjacent the cracked coffee discharged from the cracking roll, the other end of said conductor communicating with the exterior of the casing, said conductor cooperating with the cracking roll surface to form an air passage embracing a portion of the cracking roll surface adjacent, the cracked coffee discharge ,therefrom, barrier means for separating said coffee inlet and said air passage, and an air inlet for admitting air into the casing between said barrier I and said passage for movement through the pas- J sage in a direction opposed to the direction of rotation of the cracking roll for picking up coffee and chaff particles adhering to the roll surface.

5. In a coffee treating apparatus including a casing having a coffee inlet, a rotating cracking roll in communication with said inlet, and a rotating reduction roll below the cracking roll, means for removing from the streamof cracked coffee chaff and any coffee particles that may be carried along therewith and returning the coffee particles removed with the chaff back into the stream prior to-its passage of the reduction roll, said means including an air exhaust conductor extending into the casing and having an inlet end disposed between said rolls adjacent the stream' of cracked coffee from the cracking roll, air inlet passages respectively embracing portions of the inactive surfaces of said rolls, barriers associated with said rolls and positioned to respectively oppose movements of the inlet air at each passage around the associated roll in a direction away from the inlet end of the exhaust conductor. and means for separating the chaff and coffee particles from the exhaust conductor and delivering the separatedout coffee particles to the air inlet passage associated with the reduction roll for return through said passage to the cracked coflee stream;

6. The process of preparing coffee which comprises subjecting coffee to a multiple of stages of reduction with a coffee stream comprising granular coffee particles and liberated chaff flowing between said stag'es, impelling an air current into contact with said coffee stream after it has left one of said stages and between adjoining stages of reduction for removing therefrom liberated chaff, separating from said removed chaff coffee particles removed with the chaff, conducting the separated coffee particles back to the coffee stream flowing between said stages of reduction, reducing by a further of said stages of reduction said retumed coffee particles along with the main bulk of the removed particles of coffee at a point removed from but adjoining the area of reduction.

ALBERT J. HAZLE, Jl. 

